Ec0 401

Introduction to Economics –ECO401 VU

Lesson 1
INTRODUCTION TO ECONOMICS

WHAT IS ECONOMICS?
Economics is not a natural science, i.e. it is not concerned with studying the physical world like
chemistry, biology. Social sciences are connected with the study of people in society. It is not possible
to conduct laboratory experiments, nor is it possible to fully unravel the process of human decision-
making.
“Economics is the study of how we the people engage ourselves in production, distribution and
consumption of goods and services in a society.”
The term economics came from the Greek for oikos (house) and nomos (custom or law), hence "rules of
the household.
Another definition is: “The science which studies human behavior as a relationship between ends and
scarce means which have alternative uses.”

BRANCHES OF ECONOMICS
Normative economics:
Normative economics is the branch of economics that incorporates value judgments about what the
economy should be like or what particular policy actions should be recommended to achieve a desirable
goal. Normative economics looks at the desirability of certain aspects of the economy. It underlies
expressions of support for particular economic policies. Normative economics is known as statements of
opinion which cannot be proved or disproved, and suggests what should be done to solve economic
problems, i-e unemployment should be reduced. Normative economics discusses "what ought to be".
Examples:
1-A normative economic theory not only describes how money-supply growth affects inflation, but it
also provides instructions that what policy should be followed.
2- A normative economic theory not only describes how interest rate affects inflation but it also
provides guidance that what policy should be followed.

Positive economics:
Positive economics, by contrast, is the analysis of facts and behavior in an economy or “the way things
are.” Positive statements can be proved or disproved, and which concern how an economy works, i-e
unemployment is increasing in our economy. Positive economics is sometimes defined as the economics
of "what is"
Examples:
1- A positive economic theory might describe how money-supply growth affects inflation, but it does
not provide any instruction on what policy should be followed.
2- A positive economic theory might describe how interest rate affects inflation but it does not provide
any guidance on whether what policy should be followed.
We the people: includes firms, households and the government.
Goods are the things which are produced to be sold.
Services involve doing something for the customers but not producing goods.

FACTORS OF PRODUCTION
Factors of production are inputs into the production process. They are the resources needed to produce
goods and services. The factors of production are:
• Land includes the land used for agriculture or industrial purposes as well as natural resources
taken from above or below the soil.
• Capital consists of durable producer goods (machines, plants etc.) that are in turn used for
production of other goods.
• Labor consists of the manpower used in the process of production.
• Entrepreneurship includes the managerial abilities that a person brings to the organization.
Entrepreneurs can be owners or managers of firms.

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Scarcity does not mean that a good is rare; scarcity exists because economic resources are unable to
supply all the goods demanded. It is a pervasive condition of human existence that exists because
society has unlimited wants and needs, but limited resources used for their satisfaction. In other words,
while we all want a bunch of stuff, we can't have everything that we want.
Rationing is a process by which we limit the supply or amount of some economic factor which is
scarcely available. It is the distribution or allocation of a limited commodity, usually accomplished
based on a standard or criterion. The two primary methods of rationing are markets and governments.
Rationing is needed due to the scarcity problem. Because wants and needs are unlimited, but resources
are limited, available commodities must be rationed out to competing uses.

ECONOMIC SYSTEMS
There are different types of economic systems prevailing in the world.

Dictatorship:
Dictatorship is a system in which economic decisions are taken by the dictator which may be an
individual or a group of selected people.
Command or planned economy:
A command or planned economy is a mode of economic organization in which the key economic
functions – for whom, what, how to produce are principally determined by government directive. In a
planned economy, a planning committee usually government or some group determines the economy’s
output of goods and services. They decide about the optimal mix of resources in the economy. They also
decide how the factor of production needs to be employed to get optimal mix.
Free market/capitalist economy:
A free market/capitalist economy is a system in which the questions about what to produce, how to
produce and for whom to produce are decided primarily by the demand and supply interactions in the
market. In this economy what to produce is thereby determined by the market price of each good and
service in relation to the cost of producing each good and service.
In a free economy the only goods and services produced are those whose price in the market is at least
equal to the producer’s cost of producing output. When a price greater than the cost of producing that
good or service prevails, producers are induced to increase the production. If the product’s price falls
below the cost of production, producers reduce supply.
Islamic economic system:
This system is based on Islamic values and Islamic rules i-e zakat, ushr, etc. Islam forbids both the
taking and giving of interest. Modern economists, too, have slowly begun to realize the futility of
interest. The Islamic economic principles if strictly followed would eliminate the
possibility of accumulation of wealth in the hands of a few and would ensure the greater circulation of
money as well as a wider distribution of wealth. Broadly speaking these principles are (1) Zakat or
compulsory alms giving (2) The Islamic law of inheritance which splits the property of an individual
into a number of shares given to his relations (3) The forbiddance of interest which checks accumulation
of wealth and this strikes at the root of capitalism.
Pakistan case: A mixed economy
In Pakistan, there is mixed economic system. Resources are governed by both government and
individuals. Some resources are in the hand of government and some are in the hand of public. Optimal
mix of resources is decided by the price mechanism i-e by the market forces of demand and supply.
Pakistan economy thus consists of the characteristics of both planned economy and free market
economy. People are free to make their decisions. They can make their properties. Government controls
the Defence.

CIRCULAR FLOW OF GOODS & INCOME
There are two sectors in the circular flow of goods & services. One is household sector and the other is
the business sector which includes firms. Households demands goods & services, Firms supply goods &
services. An exchange takes place in an economy. In monetary economy, firms exchange goods &
services for money. Firms’ demands factors of production and households supply factors of production.
Firms pay the payment in terms of wages, rent, etc. This is circular flow of goods. On the other hand,



household gives money to firms to purchase the goods & services from firms, and firms’ gives money to
households in return for factors of production.

DISTINCTION BETWEEN MICRO & MACRO ECONOMICS
Micro Economics:
The branch of economics that studies the parts of the economy, especially such topics as markets,
prices, industries, demand, and supply. It can be thought of as the study of the economic trees, as
compared to macroeconomics, which is study of the entire economic forest. Microeconomics is a branch
of economics that studies how individuals, households, and firms make decisions to allocate limited
resources typically in markets where goods or services are being bought and sold. It also examines how
these decisions and behaviors affect the supply and demand for goods and services, which determines
prices, and how prices, in turn, determine the supply and demand of goods and services.

Macro Economics:
The branch of economics that studies the entire economy, especially such topics as aggregate
production, unemployment, inflation, and business cycles. It can be thought of as the study of the
economic forest, as compared to microeconomics, which is study of the economic trees.
Macroeconomics, involves the "sum total of economic activity, dealing with the issues of growth,
inflation, and unemployment and with national economic policies relating to these issues” and the
effects of government actions (e.g., changing taxation levels) on them.



Lesson 02
INTRODUCTION TO ECONOMICS (CONTINUED)

COST & BENEFIT ANALYSIS
Rational choice is the choice based on pure reason and without succumbing to one’s emotions or
whims. Consumers can decide about the rational decision by using cost and benefit analysis. Rational
choice is a general theory of human behavior that assumes individuals try to make the most efficient
decisions possible in an environment of scarce resources. By "efficient" it is meant that humans are
"utility maximizers" - for any given choice a person seeks the most benefit relative to costs. Consumers
can make about the rational decision by using cost and benefit analysis. Consumers want to maximize
their level of satisfaction relative to their cost. Rational choice is also the optimal choice.
Optimum means producing the best possible results (also optimal).
Equity in economics means a situation in which every thing is treated fairly or equally, i.e. according to
its due share. So if the lives of all individuals are deemed to have equal value, equity would demand that
all of them have equal financial net worth.
Nepotism means doing unfair favors for near ones when in power.
Rational choice is the choice based on pure reason and without succumbing to one’s emotions or
whims.
Barter trade is a non-monetary system of trade in which “goods” not money is exchanged. This was
the system used in the world before the advent of coins and currency.

HOW CONSUMER DECIDES ABOUT OPTIMAL CHOICE
The consumers decide about the optimal choice by using the cost and benefit analysis which maximizes
the benefit relative to the cost.
Example:
Benefit Cost Net Benefit
(Salary) (Transportation) = Benefit – Cost
Job A (Lahore) 15,000 1,000 14,000

Job B (Gujranwala) 20,000 7,000 13,000

Since net benefit of job A is greater so the rational choice is job A which is in Lahore.

HOW PRODUCERS DECIDE ABOUT OPTIMAL CHOICE
Assume that a firm which is thinking to open a new production line of car manufacturing. Rational
decision involves the cost and benefit of that car’s production.
Costs will be additional labor employed, additional raw material and additional parts & components that
have to be bought.
Benefits will be additional revenue that the firm will get by selling the additional number of cars.
It will be profitable to invest if revenue is greater than the cost.

OPPORTUNITY COST
The opportunity cost of a particular choice is the satisfaction that would have been derived from the
next best alternative foregone; in other words, it is what must be given up or sacrificed in making a
certain choice or decision.
Example:
Let’s take the decision to buy the book or not, if you will not buy the book then you will be involved in
many other activities. In the following table, opportunity Cost of buying the book and not giving charity
= 20 SU, which is the benefit derived from giving charity. You will buy the book if the benefit from
other alternatives is less than the benefit derived from buying of book.



Benefit Derived in
Cost
Satisfaction Unit
Book 200 10
Clothes 200 5
Charity 200 20

MARGINAL COST AND MARGINAL BENEFIT
Marginal cost is the increment to total costs of producing an additional unit of some good or service.
There are other broader definitions as well.
Marginal benefit is the increment to total benefit derived from consuming an additional unit of good or
service. There are other broader definitions as well.

PRODUCTION POSSIBILITY FRONTIER (PPF)
Production possibility frontier (PPF) is the curve which joins all the points showing the maximum
amount of goods and services which the country can produce in a given time with limited resources,
given a specific state of technology. A production possibilities frontier represents the boundary or
frontier of the economy's production capabilities. That's why it's termed a production possibilities
frontier (or PPF). As a frontier, it is the maximum production possible given existing (fixed) resources
and technology.
Table: Choice & Opportunity cost revisited: The law of increasing opportunity cost

Rice Cotton Opportunity Cost
(Bags) (Bushels) of Additional Unit
A 0 10
B 1 9 1
C 2 7 2
D 3 4 3
E 4 0 4

This table represents the alternative combinations of rice and cotton for a hypothetical economy which
is producing only 2 goods. At point A only cotton is produced, rice is not produced. In order to produce
one unit of rice, we have to give up one unit of cotton (10-9=1). So the opportunity cost is 1 at point B.
further in order to produce next unit of rice, we have to give up 2 units of cotton (9-7=2). So the
opportunity cost of next additional unit is 2 and so on. This table shows that opportunity cost is
increasing with each additional unit. It means we have to give up higher and higher units of cotton in
order to produce each additional unit of rice. This is the principle of increasing opportunity cost. If
opportunity cost decreases with each additional unit produced, then it is the principle of decreasing
opportunity cost. And if opportunity cost remains constant with each extra unit produced, it is the
principle of constant opportunity cost.
The law of increasing opportunity cost is what gives the curve its distinctive convex shape. Points on the
PPF show the efficient utilization of resources. Points inside the PPF show inefficient use of resources.
Points outside the PPF show that some of the resources are unemployed or not utilized. PPF curve shifts
upward due to technological advancements. If there is improvement in technology to produce the
output, then total output will increase and PPF will shift outward.

OPPORTUNITY COST & PRODUCTION POSSIBILITIES
The production possibilities analysis, which is the alternative combinations of two goods that an
economy can produce with given resources and technology, can be used to illustrate opportunity cost--
the highest valued alternative foregone in the pursuit of an activity. The PPF showed in the video lecture
slide shows the principle of increasing opportunity cost.



PPF AND ITS RELATIONSHIP WITH MACROECONOMICS

In the graph of PPF, Points within the PPF are inefficient and it is the rare possibility in the real world.
Inefficient means that it may not be using its available resources. May be some workers are unemployed
creating the macro economic problem of unemployment or may be capital is not using properly. Points
outside the PPF are unattainable since the PPF defines the maximum output produced at the given time
period so there is no possibility to produce output outside the PPF. Here in PPF, we are not concerned
with the combinations of goods which is a micro economic issue rather we are concerned with the
overall output produced which is a macroeconomic issue.

Economic growth is an increase in the total output of a country over time. It is the long-run expansion
of the economy's ability to produce output. When GDP of a country is increasing it means that country
is growing economically. Economic growth is made possible by increasing the quantity or quality of the
economy's resources (labor, capital, land, and entrepreneurship).



EXERCISES

Could production and consumption take place without money? If you think they could, give
examples.
Yes. People could produce things for their own consumption. For example, people could grow vegetables
in their garden or allotment; they could do their own painting and decorating. Alternatively people could
engage in barter: they could produce things and then swap them for goods that other people had produced.
Must goods be at least temporarily unattainable to be scarce?
Goods need not be unattainable to be scarce. Because people’s incomes are limited, they can not have
everything they want from shops, even though the shops are stocked full. If all items in shops were free,
the shelves would soon be emptied!
If we would all like more money, why does the government not print a lot more? Could it not
thereby solve the problem of scarcity ‘at a stroke’?
The problem of scarcity is one of a lack of production. Simply printing more money without producing
more goods and services will merely lead to inflation. To the extent that firms cannot meet the extra
demand (i.e. the extra consumer expenditure) by extra production, they will respond by putting up their
prices. Without extra production, consumers will be unable to buy any more than previously.
Which of the following are macroeconomic issues, which are microeconomic ones and which could
be either depending on the context?
a) Inflation.
b) Low wages in certain service industries.
c) The rate of exchange between the dollar and the rupee.
d) Why the price of cabbages fluctuates more than that of cars.
e) The rate of economic growth this year compared with last year.
f)The decline of traditional manufacturing industries.
a) Macro. It refers to a general rise in prices across the whole economy.
b) Micro. It refers to specific industries
c) Either. In a world context, it is a micro issue, since it refers to the price of one currency in terms
of one other. In a national context it is more of a macro issue, since it refers to the exchange rate
at which all Pakistanis goods are traded internationally. (This is certainly a less clear–cut division
that in (a) and (b) above.)
d) Micro. It refers to specific products.
e) Macro. It refers to the general growth in output of the economy as a whole.
f) Micro (macro in certain contexts). It is micro because it refers to specific industries. It could,
however, also help to explain the macroeconomic phenomena of high unemployment or balance
of payments problems.
Assume that you are looking for a job and are offered two. One is more unpleasant to do, but pays
more. How would you make a rational choice between the two jobs?
You should weigh up whether the extra pay (benefit) from the better paid job is worth the extra hardship
(cost) involved in doing it.
How would the principle of weighing up marginal costs and benefits apply to a worker deciding how
much overtime to work in a given week?
The worker would consider whether the extra pay (the marginal benefit) is worth the extra effort and loss
of leisure (the marginal cost).
Would it ever be desirable to have total equality in an economy?
The objective of total equality may be regarded as desirable in itself by many people. There are two
problems with this objective, however. The first is in defining equality. If there were total equality of
incomes then households with dependants would have a lower income per head than households where
everyone was working. In other words, equality of incomes would not mean equality in terms of standards
of living.



If on the other hand, equality were to be defined in terms of standards of living, then should the different
needs of different people be taken into account? Should people with special health or other needs have a
higher income? Also, if equality were to be defined in terms of standards of living, many people would
regard it as unfair that people should receive different incomes (according to the nature of their household)
for doing the same amount of work.
The second major problem concerns incentives. If all jobs were to be paid the same (or people were to be
paid according to the composition of their household), irrespective of people’s efforts or skills, then what
would be the incentive to train or to work harder?
If there are several other things you could have done, is the opportunity cost the sum of all of them?
No. It is the sacrifice involved in the next best alternative.
What is the opportunity cost of spending an evening revising for an economics exam? What would
you need to know in order to make a sensible decision about what to do that evening?
The next best alternative might be revising for another exam, or it might be taking time off to relax or to
go out. To make a sensible decision, you need to consider these alternatives and whether they are better or
worse for you than studying for the economics exam. One major problem here is the lack of information.
You do not know just how much the extra study will improve your performance in the exam, because you
do not know in advance just how much you will learn and you do not know what is going to be on the
exam paper. Similarly you do not know this information for studying for other exams.
Make a list of the benefits of higher education.
The benefits to the individual include: increased future earnings; the direct benefits of being more
educated; the pleasure of the social contacts at university or college.
Is the opportunity cost to the individual of attending higher education different from the
opportunity costs to society as a whole?
Yes. The opportunity cost to society as a whole would include the costs of providing tuition (staffing
costs, materials, capital costs, etc.), which could be greater than any fees the student may have to pay. On
the other hand, the benefits to society would include benefits beyond those received by the individual. For
example, they would include the extra profits employers would make by employing the individual with
those qualifications.
There is a saying in economics, ‘There is no such thing as a free lunch’. What does this mean?
That there is always (or virtually always) an opportunity cost of anything we consume. Even if we do not
incur the cost ourselves (the ‘lunch’ is free to us), someone will incur the cost (e.g. the institution
providing the lunch).
Are any other (desirable) goods or services truly abundant?
Very few! Possibly various social interactions between people, but even here, the time to enjoy them is
not abundant.
Under what circumstances would the production possibility curve be (a) a straight line; (b) bowed in
toward the origin? Are these circumstances ever likely?
a) When there are constant opportunity costs. This will occur when resources are equally suited to
producing either good. This might possibly occur in our highly simplified world of just two
goods. In the real world it is unlikely.
b) When there are decreasing opportunity costs. This will occur when increased specialization in
one good allows the country to become more efficient in its production. It gains ‘economies of
scale’ sufficient to offset having to use less suitable resources.
Will economic growth necessarily involve a parallel outward shift of the production possibility
curve?
No. Technical progress, the discovery of raw materials, improved education and training, etc., may favour
one good rather than the other. In such cases the gap between the old and new curves would be widest
where they meet the axis of the good whose potential output had grown more.
Which of the following are positive statements, which are normative statements and which could be
either depending on the context?
a) Cutting the higher rates of income tax will redistribute incomes from the poor to the rich.



b) It is wrong that inflation should be reduced if this means that there will be higher
unemployment.
c) It is wrong to state that putting up interest rates will reduce inflation.
d) The government should raise interest rates in order to prevent the exchange rate falling.
e) Current government policies should reduce unemployment.
a) Positive. This is merely a statement about what would happen.
b) Normative. The statement is making the value judgment that reducing inflation is a less desirable
goal than the avoidance of higher unemployment.
c) Positive. Here the word ‘wrong’ means ‘incorrect’ not ‘morally wrong’. The statement is making
a claim that can be tested by looking at the facts. Do higher interest rates reduce inflation, or
don’t they?
d) Both. The positive element is the claim that higher interest rates prevent the exchange rate falling.
This can be tested by an appeal to the facts. The normative element is the value judgment that the
government ought to prevent the exchange rate falling.
e) Either. It depends what is meant. If the statement means that current government policies are
likely to reduce unemployment, the statement is positive. If, however, it means that the
government ought to direct its policies towards reducing unemployment, the statement is
normative.



Lesson 03
Demand, Supply & Equilibrium Analysis

GOODS MARKET AND FACTORS MARKET
Goods/product/commodity markets:
Markets used to exchange final good or service. Product markets exchange consumer goods purchased
by the household sector, capital investment goods purchased by the business sector, and goods
purchased by government and foreign sectors. A product market, however, does NOT include the
exchange of raw materials, scarce resources, factors of production, or any type of intermediate goods.
The total value of goods exchanged in product markets each year is measured by gross domestic
product. The demand side of product markets includes consumption expenditures, investment
expenditures, government purchases, and net exports. The supply side of product markets is production
of the business sector.
Factors markets:
Markets used to exchange the services of a factor of production: labor, capital, land, and
entrepreneurship. Factor markets, also termed resource markets, exchange the services of factors, NOT
the factors themselves. For example, the labor services of workers are exchanged through factor markets
NOT the actual workers. Buying and selling the actual workers are not only slavery (which is illegal) it's
also the type of exchange that would take place through product markets, not factor markets. More
realistically, capital and land are two resources and are legally exchanged through product markets. The
services of these resources, however, are exchanged through factor markets. The value of the services
exchanged through factor markets each year is measured as national income.
Assumption is a belief or feeling that something is true or that something will happen, although there is
no proof. Economists make frequent use of assumptions in putting forward their theories.
Perfect competition refers to a situation in which no firm or consumer is big enough to affect the
market price.

DEMAND ANALYSIS
Shortage:
A shortage is a situation in which demand exceeds supply, i.e. producers are unable to meet market
demand for the product. Shortages cause prices to raise prompting producers to produce more and
consumers to demand less.
Surplus:
A surplus is a situation of excess supply, in which market demand falls short of the quantity supplied;
i.e. the producers are unable to sell all the produced goods in the market. Surpluses cause prices to fall
prompting producers to supply less and consumers to demand more.
Price Mechanism:
The price mechanism is a signaling and rationing device which prompts consumers and producers to
adjust their demand and supply, respectively, in response to a shortage or surplus. Shortages cause
prices to rise, prompting producers to produce more and consumers to demand less. Surpluses cause
prices to fall prompting producers to supply less and consumers to demand more. In either case, the
price mechanism attempts to clear the shortage or surplus in the market.
Normal goods are goods whose quantity demanded goes up as consumer income increases.
Inferior goods are goods whose quantity demanded goes down as consumer income increases.
Giffen goods are the sub category of inferior good. It is a rare type of good seldom seen in the real
world, in which a change in price causes quantity demanded to change in the same direction (in
violation of the law of demand). In other words, an increase in the price of Giffen good results in an
increase in the quantity demanded. The existence of a Giffen good requires the existence of special
circumstances. First, the good must be an inferior good. Second, the income effect is greater than the
substitution effect. A Giffen good is most likely to result when the good is a significant share of the
consumer's budget. Margarine is a Giffen good as compared to butter.
Substitution effect:
It is one of two reasons for law of demand and the negative slope of the market demand curve. The
substitution effect occurs because a change in the price of a good makes it relatively higher or lower



than the prices of other goods that might act as substitutes. A higher price means that a good is more
expensive relative to other goods, while a lower price means it's less expensive.
Or more simply we can say that if price of any good increases, people reduce its consumption and
substitute any other good whose price is not increased. This is substitution effect.
Income effect:
It is also one of two reasons for the law of demand and the negative slope of the market demand curve.
The income effect results because a change in price gives buyers more real income, or the purchasing
power of the income, even though money or nominal income remains the same. This causes changes in
the quantity demanded of the good.
Or more simply we can say that when price of any good increases, consumer’s real income falls and its
purchasing power also decreases. This is income effect.
Price effect:
Price effect is the addition of income and substitution effect.
Price effect = Income effect + Substitution effect
Substitutes are goods that compete with one another or can be substituted for one another, like butter
and margarine.
Compliments are goods that go hand in hand with each another. Examples are left shoe and right shoe,
or bread and butter
Cash crops are the crops which are not used as food but as a raw material in factories e.g. cotton.
DEMAND
Demand is the quantity of a good that buyers wish to purchase at each conceivable price.
Law of demand:
The law of demand states that holding all other factors constant, if the price of a certain commodity
rises, its quantity demanded will go down, and vice-versa. Other factors are income, population, tastes,
prices of all other goods etc.
Demand schedule:
A demand schedule is a table (sometimes also referred to as a graph) which shows various combinations
of quantity demanded and price.

Price Quantity demanded Quantity demanded
(Individual) (Market)
5 3.5 3500
4 4.5 4500
3 6.0 6000
2 8.0 8000
1 11.0 11000
Demand curve:
A demand curve is a graph that obtains when price (one of the determinants of demand) is plotted
against quantity demanded.

Price (P)
Demand Curve

Quantity Demanded (Q)
Demand function:
A demand function is an equational representation of demand as a function of its many determinants.



Qd = f ( Pg , T , Psi … Psn , Pci … Pcm , Y , B , Pge t+1 )
Where,
Pg = Price of the good, T = Tastes, Psi … Psn = Prices of substitute goods, Pci … Pcm = Prices of
complimentary goods, Y = Income, B = Income Distribution, Pge t+1 = Future prices
Equation of demand function is Qd= a – b P
Shifts in the demand curve:
Shifts in the demand curve plotted in P-Qd space are caused by changes in any determinant of demand
other than the price of the good itself. Movements along the curve correspond to the changes in the
variable on the vertical axis.

FACTORS SHIFTING DEMAND CURVE:

Factors Changing Effect on Direction of Effect on Effect on
Demand Demand Shift in Demand Equilibrium Equilibrium
Curve Price Quantity
Increase in income Increase Rightward Increase Increase
(normal good)
Decrease in Decrease Leftward Decrease Decrease
income(normal good)
Increase in income Decrease Leftward Decrease Decrease
(inferior good)
Decrease in Increase Rightward Increase Increase
income(inferior good)
Increase in price of Increase Rightward Increase Increase
Substitute
Decrease in price of Decrease Leftward Decrease Decrease
substitute
Increase in price of Decrease Leftward Decrease Decrease
complement
Decrease in price of Increase Rightward Increase Increase
complement
Increase in taste and Increase Rightward Increase Increase
preference for good
Decrease in taste and Decrease Leftward Decrease Decrease
preference for good
Increase in number of Increase Rightward Increase Increase
consumers
Decrease in number of Decrease Leftward Decrease Decrease
consumers

MARKET DEMAND CURVE
Market demand curve is a graphic representation of a market demand which shows the quantities of a
commodity that consumers are willing and able to purchase during a period of time at various alternative
prices, while holding constant everything else that effects demand. The market demand curve for a
commodity is negatively sloped, indicating that more of a commodity is purchased at a lower price.



Lesson 04
DEMAND, SUPPLY & EQUILIBRIUM ANALYSIS (CONTINUED)

SUPPLY
Supply is the quantity of a good that sellers wish to sell at each conceivable price.
Law of supply:
The law of supply states that the quantity supplied will go up as the price goes up and vice versa. As
output increases, cost will also increase. Higher prices means more profit so firms will produce more of
that product whose price has increased. New producers will also emerge in the market. And total supply
will also increase.
Supply schedule:
A supply schedule is a table (sometimes also referred to as a graph) which shows various combinations
of quantity supplied and price.

Price Quantity supplied Quantity supplied
(Individual) (Market)
5 75 7500
4 70 7000
3 60 6000
2 40 4000
1 10 1000

Supply curve:
A supply schedule is a table which shows various combinations of quantity supplied and price.
Graphical illustration of this table gives us the supply curve.

Price (P)

Supply Curve

Quantity Supplied (Q)
Supply function:
A supply function is an equational representation of supply as a function of all its determinants.
Quantity Supplied = f (Price)
QS = f ( Pg , Cg , a1 … an , j1 … jm , R , A , Pge t+1 )
Where,
Quantity Supplied = Qs, Price of the goods = Pg, Profitability of alternative goods = a1…..an,
Profitability of the goods jointly supplied = j1….jm, Nature and Other Random Shocks = R, Aims of
Producers = A, Expected Price of good = Pge at some future time = t+1
A supply equation is QS = c + d P

PROBLEMS OF IDENTIFICATION OR DETERMINANTS OF SUPPLY
Problems of identification arise when we can not determine that the change in the equilibrium quantities
is either caused by a change in demand or by changes in both demand and supply.
Determinants of supply are:
• Costs of production
• Profitability of alternative products (substitutes in supply)
• Profitability of goods in joint supply



• Nature and other random shocks
• Aims of producers
• Expectations of producers
Determinants in the context of supply of butter:
• A reduction in the cost of producing butter.
• A reduction in the profitability of producing cream or cheese.
• An increase in the profitability of skimmed milk.
• If weather conditions are favorable, grass yields and hence milk yields are likely to be high.
• If butter producers expect the price to rise in near future, they may decide to release less to the
market now.

FACTORS SHIFTING SUPPLY CURVE

Factors Changing Supply Effect on Direction of Effect on Effect on
Supply Shift in Supply Equilibrium Equilibrium
Curve Price Quantity
Increase in resource price Decrease Leftward Increase Decrease
Decrease in resource price Increase Rightward Decrease Increase
Improved technology Increase Rightward Decrease Increase
Decline in technology Decrease Leftward Increase Decrease
Expect a price increase Decrease Leftward Increase Decrease
Expect a price decrease Increase Rightward Decrease Increase
Increase in number of Increase Rightward Decrease Increase
suppliers
Decrease in number of Decrease Leftward Increase Decrease
suppliers

EQUILIBRIUM
Equilibrium is a state in which there are no shortages and surpluses; in other words the quantity
demanded is equal to the quantity supplied.
Equilibrium price is the price prevailing at the point of intersection of the demand and supply curves; in
other words, it is the price at which the quantity demanded is equal to the quantity supplied.
Equilibrium quantity is the quantity that clears the market; in other words, it is it is the quantity at which
the quantity demand is equal to the quantity supplied.

Demand Curve
Price (P) Supply Curve

Qd = Qs

Quantity (Q)

ALGEBRAIC REPRESENTATION OF EQUILIBRIUM
If we have following demand and supply function
Qd = 100 – 10 P
Qs = 40 + 20 P



In equilibrium,
Qd = Qs
Therefore,
100 - 10P = 40 + 20P
20P + 10P = 100 - 40
30P = 60
P = 60/30
P=2

Putting the value of price in any of demand and supply equation,

Q = 100 – 10x2 (or 40 + 20x2)
Q = 100 – 20
Q = 80

The equilibrium price is 2 and the equilibrium quantity is 80



Lesson 05
DEMAND, SUPPLY & EQUILIBRIUM ANALYSIS (CONTINUED)

EQUILIBRIUM CAN SHIFT IF
• Demand Curve Shifts.
• Supply Curve Shifts.
• Both Shift.
This gives rise to eight possibilities. These eight possibilities can be summarized as following:
D , S ~, P Q
D~,S , P Q
D ,S , P? Q
D ,S~, P Q
D~,S , P Q
D ,S , P Q?
D ,S , P Q?
D ,S , P? Q

The symbol “ ” or “ ” shows increase and the symbol “ ” and “ ” shows a decrease while the
symbol “~” shows that the particular thing remains same.

NOTE: (Graphical illustration of all these possibilities is given in the video lecture)
Points to note in these 8 possibilities:
1. Whenever the demand curve shifts the new equilibrium is obtained by moving along the supply
curve.
2. Whenever supply curve shifts, the new equilibrium is obtained by moving along the demand
curve.
3. Whenever both demand and supply curves shifts, we will move first on the demand curve and
then along the supply curve.

THE MARKET FOR BUTTER
Question: What will happen to the equilibrium price and quantity of butter in each of the following
cases?
a. A rise in the price of the margarine. D , S
b. A rise in the demand for milk. S ; D ( if milk is a substitute )
c. A rise in the price of bread. D
d. A rise in the demand of bread. D
e. An expected rise in the price of butter in near future. S D
f. A Tax on butter production. S
g. An invention of a new, but expensive, process of removing all cholesterol from butter , plus the
passing of law which states that all producers must use this process. D S

GOVERNMENT’S ROLE IN PRICE-DETERMINATION & EQUILIBRIUM ANALYSIS
Identification problem is the problem of how to identify demand & supply curve. This problem arises
when both price and quantity.
Government can impact on equilibrium by two fundamental ways. The government may intervene in the
market and mandate a maximum price (price ceiling) or minimum price (price floor) for a good or
service.

PRICE CEILING:
A price ceiling is the maximum price limit that the government sets to ensure that prices don’t rise
above that limit (medicines for e.g.).



If a price ceiling is placed below the market-clearing price, as Pc, the market-clearing or equilibrium
price of Pe becomes illegal. At the ceiling price, buyers want to buy more than sellers will make
available. In the graph, buyers would like to buy amount Q4 at price Pc, but sellers will sell only Q1.
Because they cannot buy as much as they would like at the legal price, buyers will be out of
equilibrium. The normal adjustment that this disequilibrium would set into motion in a free market, an
increase in price, is illegal; and buyers or sellers or both will be penalized if transactions take place
above Pc. Buyers are faced with the problem that they want to buy more than is available. This is a
rationing problem.

PRICE FLOOR:
A price floor is the minimum price that a Government sets to support a desired commodity or service in
a society (wages for e.g.).

Price ceilings are not the only sort of price controls governments have imposed. There have also been
many laws that establish minimum prices, or price floors. The graph illustrates a price floor with price
Pf. At this price, buyers are in equilibrium, but sellers are not. They would like to sell quantity Q2, but
buyers are only willing to take Q3. To prevent the adjustment process from causing price to fall,
government may buy the surplus, If it does not buy the surplus, government must penalize either buyers
or sellers or both who transact below the price floor, or else price will fall. Because there is no one else
to absorb the surplus, sellers will.



RATIONING & SUPPLY SHOCKS (ALTERATION OF EQUILIBRIUM PRICE BY THE
GOVT)
There are two ways for this:
1. Through Tax :
Tax (to be paid by the producer) will increase the Supply Price, Supply Curve shifts left ward, Price
increases & quantity decreases.
2. Through Subsidy :
Subsidy (given to the producer) will decrease the Supply Price, Supply Curve shifts rightward, Price
decreases & quantity increases.

SOCIAL COST
Social cost is the cost of an economic decision, whether private or public, borne by the society as a
whole.
MARGINAL SOCIAL COST
Marginal social cost is the change in social costs caused by a unit change in output.



EXERCISES

Asif and Aasia’s “monthly” demand schedules for potatoes are given. Roughly draw these demand
schedules on the same graph. Assume that there are 200 consumers in the market. Of these, 100
have schedules like Asif’s and 100 have schedules like Aasia’s. Complete the Total market demand
(“monthly”) column in the table below?
Price Asif Aasia Total
market
demand
(pence (Qd in (Qd in (kg)
per kg) kg) kg)
20 28 16 4400
40 15 11 2600
60 5 9 1400
80 1 7 800
100 0 6 600

100

90

80

70

60
Price in Rs/kg

50

40
Asif’s
30 demand
Aasia’s
20 demand
10

0
0 5 10 15 20 25 30
Quantity demanded (kg per month)

Assuming that demand does not change from month to month, how would you plot the annual
market demand for potatoes?
The amount demanded would be 12 times higher at each price. If the scale of the horizontal axis were
unaltered, the curve would shift way out to the right. A simple way of showing the new curve, therefore,
would be to compress the scale of the horizontal axis. (If each of the numbers on the axis were multiplied
by 12, the curve would remain in physically the same position.)
At what price is their demand the same?
The two curves cross at a price of Rs50 per kg and at a demand of 10 kg per month.
What explanations could there be for the quite different shapes of their two demand curves?
One explanation could be that Asif is quite happy to eat rice, pasta or bread instead of potatoes. Thus
when the price of potatoes goes up she switches to these other foods, and switches to potatoes when the
price of potatoes comes down. Aasia, by contrast, may not see these other foods as close substitutes and
thus her demand for potatoes will be less price sensitive.



Do all these the determinants of demand affect both an individual’s demand and the market
demand for a product?
All except the distribution of income in the economy.
You are given a market demand curve for apples. Assume that the price of apples increases by 20
per cent at each price – due, say, to substantial increases in the prices of other substitute fruits. Plot
the new demand curve for apples. Is the new curve parallel to the old one?
See below. As you can see, the curves are not parallel. A constant percentage increase in quantity
demanded gives a bigger and bigger absolute increase as quantity increases.

100

90
80

70
Price (Rs per kg)

60

50

40
New
30 demand
20 Old
demand
10

0
0 100 200 300 400 500 600 700 800 900
Quantity demanded (kg per month)

The price of lamb meat rises and yet it is observed that the sales of lamb meat increase. Does this
mean that the demand curve for lamb meat is upward sloping? Explain.
No not necessarily. For example, the price of substitutes such as beef or chicken may have risen by a
larger amount. In such cases the demand curve for lamb meat will have shifted to the right. Thus
although a rise in the price of lamb meat will cause a movement up along this new demand curve, more
lamb meat will nevertheless be demanded because lamb meat is now relatively cheaper than the
alternatives.
A demand function is given by Qd = 10000 – 200P. Draw this in P-Qd space. What is it about the
demand function equation that makes the demand curve in P- Qd space (a) downward sloping; (b) a
straight line?
a) The fact is that the 200P term has a negative sign attached to it. This means that as P rises, Qd
falls.
b) The fact is that there is no P to a power term. The demand curve thus has a constant slope of –
1/200.
A demand function is given by Qd = a + bY, where Y is total income. If the term “a” has a value of –
50 000 and the term “b” a value of 0.001, construct a demand schedule with respect to Y. Do this
for incomes between Rs100 million and Rs300 million at Rs50 million intervals.



Y (in Rs Qd (in 000s)
millions)

100 50
150 100
200 150
250 200
300 250

Now use this schedule to plot a demand curve with respect to income. Comment on its shape.
The curve will be an upward-sloping straight line, crossing the horizontal axis at –50 000. It would rise by
100 000 units for each Rs100 million rise in income.
300
Demand

250
Income (Rs millions

200

150

100

50

0
0 50 100 150 200 250 300
Quantity demanded
Market dem and (with respect to income)

What are the reasons which cause the market supply of potatoes to fall?
Examples include:
• The cost of producing potatoes rises.
• The profitability of alternative crops (e.g. carrots) rises.
• A poor potato harvest.
• Farmers expect the price of potatoes to rise (short-run supply falls).
For what reasons might the supply of leather rise?
Examples include:
• The cost of producing leather falls.
• The profitability of producing mutton and chicken decreases.
• The price of beef rises (goods in joint supply).
• A long-running industrial dispute involving leather workers is resolved.
• Producers expect the price of leather to fall (short-run supply increases).
This question is concerned with the supply of gas for home and office heating in winters. In each
case consider whether there is a movement along the supply curve (and in which direction) or a shift
in it (left or right). (a) New gas fields start up in production. (b) The demand for home heating rises.
(c) The price of electric heating falls. (d) The demand for CNG for cars (produced in joint supply)
rises. (e) New technology decreases the costs of gas production.
(a) Shift right. (b) Movement up along (as a result of a rise in price). (c) Movement down along (as a result
of a fall in price resulting from a fall in demand as people switch to electric heating). (d) Shift right (more
of a good in joint supply is produced). (e) Shift right.



A supply function is given as Qs = c + dP, where “c” is 500 and “d” is 1000. Draw the schedule
(table) and graph for equation for prices from Rs1 to Rs10. What is it in the equation that
determines the slope of the supply ‘curve’?

10
9
Supply
8
7
6
Price
5
4
3
2
1
0
0 2000 4000 6000 8000 10000
Quantity supplied

P (in Qs
Rs) (units)

1 1500
2 2500
3 3500
4 4500
5 5500
6 6500
7 7500
8 8500
9 9500
10 10500

The graph is an upward sloping straight line crossing the horizontal axis at 500 units. The slope is given
by the value of the d term: i.e. the slope is 1/1000 (for every Re1 increase in price, quantity supplied
increases by 1000 units).
Explain the process by which the price of houses would rise if there were a shortage.
People with houses to sell would ask a higher price than previous sellers of similar houses (probably with
the advice of an estate agent). Potential purchasers would be prepared to pay a higher price than
previously in order to obtain the type of house they wanted.
With a typical upward sloping market supply curve and downward sloping market demand curve,
what would happen to equilibrium price and quantity if the demand curve shifted to the left?
Both price and quantity will fall. You should be able to label two demand curves (e.g. D1 and D2), two
equilibrium points (e.g. e1 and e2) corresponding prices Pe2 and Pe1 (Pe2 < Pe1), and quantities Qe2 and Qe1
(Qe2 > Qe1).
What will happen to the equilibrium price and quantity of butter in each of the following cases?
You should state whether demand or supply (or both) have shifted and in which direction. (In each
case assume ceteris paribus.)
(a) A rise in the price of margarine; (b) A rise in the demand for yoghurt; (c) A rise in the price of
bread; (d) A rise in the demand for bread; (e) An expected rise in the price of butter in the near
future; (f) A tax on butter production; (g) The invention of a new, but expensive, process for



removing all cholesterol from butter plus the passing of a law which states that all butter producers
must use this process.
a) Price rises, quantity rises (demand shifts to the right: butter and margarine are substitutes).
b) Price falls, quantity rises (supply shifts to the right: butter and yoghurt are in joint supply).
c) Price falls, quantity falls (demand shifts to the left: bread and butter are complementary goods).
d) Price rises, quantity rises (demand shifts to the right: bread and butter are complementary goods).
e) Price rises, quantity rises or falls depending on relative sizes of the shifts in demand and supply
(demand shifts to the right as people buy now before the price rises; supply shifts to the left as
producers hold back stocks until the price does rise).
f) Price rises, quantity falls (supply shifts to the left).
g) Price rises, quantity rises or falls depending on the relative size of the shifts in demand and supply
(demand shifts to the right as more health-conscious people start buying butter; supply shifts to the
left as a result of the increased cost of production).
Are there any factors on the supply side that influence house prices?
Yes. Although they are usually less important than demand-side factors, they are, nevertheless important
in determining changes in house prices. The two most important are the expectations of the construction
industry. If house building firms (contractors) are confident that demand will continue to rise, and with it
house prices, they are likely to start building more houses. The resulting increase in the supply of houses
(after the time taken to build them) will help to dampen the rise in prices.
The other major supply-side factor is the expectations of house owners. If people think that prices will rise
in the near future and are thinking of selling their house, they are likely to delay selling and wait until
prices have risen. This (temporary) reduction in supply will help to push up prices even further.
Draw a supply and demand diagram with the price of labour (the wage rate) on the vertical axis and
the quantity of labour (the number of workers) on the horizontal axis. What will happen to
employment if the government raises wages from the equilibrium to some minimum wage above the
equilibrium?
Firms’ demand for labour will shrink at the new higher wage rate. The supply of workers will rise as more
workers would be willing to work (and work more hours) at the higher wage rate. There will thus be
unemployment (a surplus of workers) at the minimum wage set.
All economies have black markets in goods; whether this poses a serious problem is another matter.
What would be the effect on black-market prices of a rise in the official price?
Other things being equal, there would probably be a fall in the black-market price. A rise in the official
price would cause an increase in the quantity supplied and a reduction in the quantity demanded and hence
less of a shortage. There would therefore be less demand for black-market products.
Will a system of low official prices plus a black market be more equitable or less equitable than a
system of free markets?
More equitable if the supplies at official prices were distributed fairly (e.g. by some form of rationing). If,
however, supplies were allocated on a first-come, first-served basis, then on official markets there would
still be inequity between those who are lucky enough or queue long enough to get the product and those
who do not get it. Also, the rich will still be able to get the product on the black market!
Think of some examples where the price of a good or service is kept below the equilibrium (e.g. rent
controls). In each case consider the advantages and disadvantages of the policy.
Two examples are:
• Rent controls.
Advantages: makes cheap housing available to those who would otherwise have difficulty in
affording reasonable accommodation. Disadvantages: causes a reduction in the supply of private
rented accommodation; causes demand to exceed supply and thus some people will be unable to find
accommodation.
• Tickets for a concert.



Advantages: allows the price to be advertised in advance and guarantees a full house; makes seats
available to those who could not afford the free-market price. Disadvantages: causes queuing or seats
are being only available to those booking well in advance.
Primary and secondary schooling is free in state schools in most countries. If parents are given a
choice of schools for their children, there will be a shortage of places at popular schools. What
methods could be used for dealing with this shortage? What are their relative merits?
Some form of rationing (selection) will have to be applied. This could be done on the basis of ability. If
the objective is to have schools that cater for the full range of abilities, then this objective will not be met.
If the objective is to recruit the most able children, then selection by ability is consistent with this goal. An
alternative is to select by geographical location, with the students living nearer to the school being given
preference over those living further away. This is the system used by most state schools. It could well
disadvantage children with particular needs, however, for whom the school would be particularly suitable.
Other methods include the ‘sibling’ rule, whereby children who have older brothers or sisters already at
the school are given preference. This, however, could lead to children living nearer the school being
deprived of a place.
Under what circumstances would making a product illegal (a) cause a fall in its price; (b) cause the
quantity sold to fall to zero.
a) Where the shift in demand was greater than the shift in supply (perhaps because of very ‘law
abiding’ consumers, or where consumers faced harsher penalties than suppliers.
b) Where the penalties were very harsh and the law was strictly enforced, and/or where people were
very law abiding.
Can you think of any examples where prices and wages do not adjust very rapidly to a shortage or
surplus? For what reasons might they not do so?
Many prices set by companies are adjusted relatively infrequently: it would be administratively too
costly to change them every time there was a change in demand. For example a mail order
company, where all the items in its catalogue have a printed price, would find it costly to adjust
prices very frequently, since that would involve printing a new catalogue, or at least a new price
list.
Many wages are set annually by a process of collective bargaining. They are not adjusted in the
interim.
Why do the prices of fresh vegetables fall when they are in season? Could an individual farmer
prevent the price falling?
Because supply is at a high level. The increased supply creates a surplus which pushes down the price.
Individual farmers could not prevent the price falling. If they continued to charge the higher price,
consumers would simply buy from those farmers charging the lower price.
If you were the owner of a clothes shop, how would you set about deciding what prices to charge for
each garment at the end of season sale?
You would try to reduce the price of each item as little as was necessary to get rid of the remaining stock.
The problem for shop owners is that they do not have enough information about consumer demand to
make precise calculations here. Many shops try a fairly cautious approach first, and then, if that is not
enough to sell all the stock, they make further ‘end of sale’ reductions later.
The number of owners of CD players has grown rapidly and hence the demand for CDs has also
grown rapidly. Yet the prices of CDs have fallen. How could this come about?
• The costs of manufacturing CDs may have fallen with improvements in technology and mass-
production economies.
• Competition from increased numbers of manufacturers may have increased supply of CDs and
driven prices down.
• The advent of copying tracks from the internet reduces the demand for CDs. This change in demand
has further compounded the fall in price.
Explain in words what is happening in the following diagram.



T h e p r ic e m e c h a n is m : t h e e f f e c t o f t h e d i s c o v e r y o f r a w m a t e r ia l s

F a c to r M a rk e t
Si ↓
Si ↑ s u rp lu s Pi ↓ u n t il D i = S i
( S i > D i) Di ↑

G o o d s M a rk e t
Sg ↓
Pi ↓ Sg ↑ s u rp lu s Pg ↓ u n t il D g = S g
(S g > D g) Dg ↑

The new discovery of raw material i means an increase in the supply i. This causes a surplus (excess
supply) in the market for i, causing the price of i to fall until the same is removed (lower Pi causes demand
to increase and supply to fall). The reduction in Pi also reduces the cost of producing good g (we can
assume good g uses the factor i intensively), causing the supply of good g to increase beyond demand. The
surplus in the market for good g drives the price of g down until the excess is cleared. The diagram
illustrates interdependence between goods and factor markets.
Can different factor markets be interdependent also? Give examples.
Yes. A rise in the price of one factor (e.g. oil) will encourage producers to switch to alternatives (e.g.
coal). This will create a shortage of coal and drive up its price. This will encourage increased production
of coal. Similarly an increase in the population (and consequently size of the labour force) of a country
will depress the price of labour (wages). This will cause producers to shift to more labour intensive
production and reduce production methods which are capital (or machine) intensive. As a result the
demand for capital will fall reducing its rental price.



Lesson 06
ELASTICITIES

IMPORTANCE OF ELASTICITY IN OUR TODAY’S LIFE
There is much more importance of the concept of elasticity in our life.
The firm which uses advertising to change prices uses the concept of elasticity of demand of its
product.
Mostly firms set the prices of their product by viewing at the elasticity of demand of their
product.
The government collects revenues by imposing taxes. The good tax imposed by the government
on the products is one for which either demand is inelastic or the supply is inelastic.
So if the government wants to put tax burden on the consumers then it will choose the product
to tax with low price elasticity of demand.
And if government wants to panelize the producers then it must choose the product with low
price elasticity of supply.

ELASTICITY
Elasticity is a term widely used in economics to denote the “responsiveness of one variable to changes
in another.” In proper words, it is the relative response of one variable to changes in another variable.
The phrase "relative response" is best interpreted as the percentage change.

TYPES OF ELASTICITY
There are four major types of elasticity:
• Price Elasticity of Demand
• Price Elasticity of Supply
• Income Elasticity of Demand
• Cross-Price Elasticity of Demand
Price Elasticity of Demand:
Price elasticity of demand is the percentage change in quantity demanded with respect to the percentage
change in price.
Price elasticity of demand can be illustrated by the following formula:

PЄd = Percentage change in Quantity Demanded
Percentage change in Price

Where Є = Epsilon; universal notation for elasticity.
If, for example, a 20% increase in the price of a product causes a 10% fall in the Quantity demanded,
the price elasticity of demand will be:
PЄd = - 10% = - 0.5
20%
Price Elasticity of Supply:
Price elasticity of supply is the percentage change in quantity supplied with respect to the percentage
change in price.
Price elasticity of supply can be illustrated by the following formula:

PЄs = Percentage change in Quantity Supplied
Percentage change in Price

If a 15% rise in the price of a product causes a 15% rise in the quantity supplied, the price elasticity of
supply will be:
PЄs = 15 % = 1
15 %



Income Elasticity of Demand:
Income elasticity of demand is the percentage change in quantity demanded with respect to the
percentage change in income of the consumer.
Income elasticity of demand can be illustrated by the following formula:

YЄd = Percentage change in Quantity Demanded
Percentage change in Income

If a 2% rise in the consumer’s incomes causes an 8% rise in product’s demand, then the income
elasticity of demand for the product will be:
YЄd = 8% =4
2%
Cross-Price Elasticity of Demand:
Cross price elasticity of demand is the percentage change in quantity demanded of a specific good, with
respect to the percentage change in the price of another related good.

PbЄda = Percentage change in Demand for good a
Percentage change in Price of good b

If, for example, the demand for butter rose by 2% when the price of margarine rose by 8%, then the
cross price elasticity of demand of butter with respect to the price of margarine will be.
PbЄda = 2% = 0.25
8%

If, on the other hand, the price of bread (a compliment) rose, the demand for butter would fall. If a 4%
rise in the price of bread led to a 3% fall in the demand for butter, the cross-price elasticity of demand
for butter with respect to bread would be:
PbЄda = - 3% = - 0.75
4%

WHY WE USE PERCENTAGE CHANGE RATHER THAN ABSOLUTE CHANGE IN
ELASTICITY?

1. By using percentage changes and proportions we can avoid the problem of comparison in two
different quantitative variables i-e Qd is measured in units and Price is measured in rupees. So
by calculating percentages we can avoid the problem of unit conversion into rupees.
2. It helps us avoid that of what size of units to be changed i-e A jump from Rs.2 to Rs.4 could be
described as a 100% increase or as an increase of Rs.2. but by using percentages we can avoid
this problem because both gives the same answer.
3. It also helps how to define big or small changes. By looking at Rs.2 or Rs.4, we can’t say that it
is a big change or a small change. But if we translate it in the form of percentages then it
becomes 100% which is a big change.

ELASTIC AND INELASTIC DEMAND
Slope and elasticity of demand have an inverse relationship. When slope is high elasticity of demand is
low and vice versa.
When the slope of a demand curve is infinity, elasticity is zero (perfectly inelastic demand); and when
the slope of a demand curve is zero, elasticity is infinite (perfectly elastic demand).
Unit elasticity means that a 1% change in price will result in an exact 1% change in quantity demanded.
Thus elasticity will be equal to one. A unit elastic demand curve plots as a rectangular hyperbola. Note
that a straight line demand curve cannot have unit elasticity as the value of elasticity changes along the
straight line demand curve.



Elastic demand curve

Inelastic demand curve

TOTAL REVENUE AND ELASTICITY
Total revenue (TR) = Price x Quantity (P x Q)
Elastic demand means when price of any product increases, its demand decreases more than the
increase in price. As price increases total revenue decreases in case of elastic demand.
Inelastic demand of any product means that if price of that product increases there is very small effect
on its quantity demanded. As price increases, total revenue also increases in case of inelastic demand.
For example, flour is the basic necessity of life for all people. Its demand is inelastic. As the price of
flour increases, its quantity demanded does not decrease much because people have to use flour in all
situations whether its price is high or low.

EXAMPLE OF 2 FIRMS
Firm 1: (Inelastic demand curve)
For inelastic demand curve, firm increases its prices but quantity demanded does not change as much.
Increase in price is greater while the decrease in quantity is smaller. So firm will earn more revenues by
increasing prices. So TR increases as the price increases.



Price

10 F

Inelastic demand
curve

6 T

0 90 100 Quantity
Demanded

Є = percentage change in Qd
Percentage change in P
= 90 – 100 ÷ 10 – 6
100 6
= - 0.15
In the above figure, Elasticity for firm 1 is equal to -0.15; it is less than 1 (ignoring minus sign) which
shows that the demand curve is inelastic.

Firm 2: (Elastic demand curve)
For elastic demand curve, firm does not increase its prices. Because as prices increases, quantity
demanded decreases much larger. Decrease in quantity demanded is greater than the increase in prices.
So firm will earn less revenue. So TR decreases as price increases.

Price

10

7 U

Z
6

0 40 100 Quantity
Demanded

Є = percentage change in Qd
= 40 – 100 ÷ 7 – 6
100 6
= - 3. 6
In the above figure elasticity for firm 2 is -3.6; it is greater than 1 (ignoring minus sign) which shows
that the demand curve is elastic.

ELASTICITY BETWEEN TWO POINTS
Elasticity can also be calculated between two points.
Figure:



Price

10


8 K

L
6

0 8 16 Quantity
Demanded

In this figure, elasticity from point K to L is -4.
ЄKL = percentage change in Qd
= 16– 8 ÷ 6 – 8
8 8
= -4
Since absolute value is greater than 1 so it is elastic.
Similarly we can also calculate for inelastic demand curve.
Arc Elasticity
Arc elasticity measures the “average” elasticity between two points on the demand curve. The formula
is simply (change in quantity/change in price)*(average price/average quantity).

To measure arc elasticity we take average values for Q and P respectively.
Point Elasticity
Point elasticity is used when the change in price is very small, i.e. the two points between which
elasticity is being measured essentially collapse on each other. Differential calculus is used to calculate
the instantaneous rate of change of quantity with respect to changes in price (dQ/dP) and then this is
multiplied by P/Q, where P and Q are the price and quantity obtaining at the point of interest. The
formula for point elasticity can be illustrated as:
Є=∆Q x P
∆P Q
Or this formula can also be written as:
Є= dQ x P
dP Q
Where d = infinitely small change in price.
If elasticity = zero then demand curve will be vertical.
If elasticity is infinity then the demand curve will be horizontal.

POINT ELASTICITY FOR QUADRATIC DEMAND FUNCTION
The quadratic demand function is
Qd = 60 – 15P + P2
Assume different values of price e-g from 0 to 10. Put these values in this equation and find out the
quantity demand. Here we take price from 0 to 3.



P 60 -15P P2 Qd = 60 – 15P + P2
0 60 0 0 60
1 60 -15 1 46
2 60 -30 4 34
3 60 -45 9 24

Then draw a figure, plot prices on vertical axis and quantity on horizontal axis. The resulting curve will
be downward sloping curve.
7
6
5
4
3
2
1
0
0 20 40 60 80

To find the point elasticity of demand from this quadratic equation, differentiate it with respect to price,

Qd = 60 – 15P + P2

dQ/dP = -15 + 2P

IF P=3 then

dQ/dP = -15 + 2(3)
= -15 + 6
= -9
And

Qd = 60- 15(3) + (3)2
= 24

The formula of elasticity = (dQ / dP) (P/Q)
= -9 (3/24)
= -1.125
Its absolute value (ignoring minus sign) is greater than one so it is point elastic.



Lesson 07
ELASTICITIES (CONTINUED)

INELASTIC DEMAND 0< Є < 1
• Price rises:
As P increases, Q decreases
Percentage change in P > percentage change in Q
Now TR = P x Q TR will also increase
• Price falls:
As P decreases, Q increases
Percentage change in P > percentage change in Q
Now TR = P x Q TR will also decrease

ELASTIC DEMAND Є > 1
• Price rises:
Percentage change in P < percentage change in Q
Now TR = P x Q TR will also decrease
• Price falls:
Percentage change in P < percentage change in Q
Now TR = P x Q TR will also increase

UNIT ELASTIC DEMAND Є = 1
• Price rises:
Percentage change in P = percentage change in Q.
Now TR = P x Q TR will remain unchanged.
• Price falls:
Percentage change in P = percentage change in Q.
Now TR = P x Q TR will remain unchanged.

TABLE OF UNITARY ELASTICITY
P Q TR
2.5 400 1,000
5 200 1,000
10 100 1,000
20 50 1,000
40 25 1,000

The curve of unitary elastic demand will be a hyperbola.
DETERMINANTS OF PRICE ELASTICITY OF DEMAND
1. Number of close substitutes within the market - The more (and closer) substitutes available in the
market the more elastic demand will be in response to a change in price. In this case, the substitution
effect will be quite strong.
2. Percentage of income spent on a good - It may be the case that the smaller the proportion of income
spent taken up with purchasing the good or service the more inelastic demand will be.
3. Time period under consideration - Demand tends to be more elastic in the long run rather than in
the short run. For example, after the two world oil price shocks of the 1970s - the "response" to higher
oil prices was modest in the immediate period after price increases, but as time passed, people found
ways to consume less petroleum and other oil products. This included measures to get better mileage



from their cars; higher spending on insulation in homes and car pooling for commuters. The demand for
oil became more elastic in the long-run.

EFFECTS OF ADVERTISING ON DEMAND CURVE
Advertising aims to:
• Change the slope of the demand curve – make it more inelastic. This is done by generating
brand loyalty;
• Shift the demand curve to the right by tempting the people’s want for that specific product.

PRICE ELASTICITY OF SUPPLY
The relative response of a change in quantity supplied to a relative change in price. More specifically
the price elasticity of supply can be defined as the percentage change in quantity supplied due to a
percentage change in supply price.

Inelastic Supply Curve
Price (P)
Unitary elastic Supply Curve

Elastic Supply Curve

Quantity Supplied (Q)

• Calculating elasticities between two points at the same curve involves arc elasticity method.
• While calculating elasticity at a certain point involves point elasticity method.

DETERMINANTS OF PRICE ELASTICITY OF SUPPLY
• If costs increases, lower will be the supply. Lower the costs the more will be the supply.
• Amount of time given to quantity respond to a price increase or decrease. There may be
immediate time period, short term and long term time period.



Lesson 08
ELASTICITIES (CONTINUED)

INCOME ELASTICITY OF DEMAND
The relative response of a change in demand to a relative change in income. More specifically the
income elasticity of demand can be defined as the percentage change in demand due to a percentage
change in buyers' income. The income elasticity of demand quantitatively identifies the theoretical
relationship between income and demand.
Єdy = ∆ Q ÷ ∆ Y
Q Y
Less income elastic Єdy < 1
Income (Y)

More income elastic Єdy > 1

Quantity demanded (Q)
If the sign of income elasticity of demand is positive, the good is normal and if sign is negative, the
good is inferior.
Table:
Quantity Demanded
Income (Rs)
(units)
10000 100
12000 105

YЄd = ∆ Q ÷ ∆ Y
Q Y
= 5 ÷ 2000
100 10000
= 0.25
The Good is normal (the sign is positive). But its demand is income inelastic o< | Є | < 1.

DETERMINANTS OF INCOME ELASTICITY OF DEMAND
The determinants of income elasticity of demand are:
• Degree of necessity of good.
• The rate at which the desire for good is satisfied as consumption increases
• The level of income of consumer.
Short Run and Long Run
Short run is a period in which not all factors can adjust fully and therefore adjustment to shocks can
only be partial.
Long run is a period over which all factors can be changed and full adjustment to shocks can take place.



MINISTRY OF AGRICULTURE REPORT
Food Stuff YЄd
Milk -0.40
Eggs -0.41
Mutton -0.21
Bread -0.25
Butter -0.04
MargarIne -0.44
Sugar -0.54
Fresh Potatoes -0.48
Tea -0.56
Cheese 0.19
Beef 0.08
Cakes&Buiscuits 0.02
Fresh Green Vegetables 0.13
Fresh Fruit 0.48
Fresh Juices 0.94
Coffee 0.23
ElasticIty For All Food -0.01

CROSS-PRICE ELASTICITY OF DEMAND
Cross price elasticity of demand is the percentage change in quantity demanded of a specific good, with
respect to the percentage change in the price of another related good.

PbЄda = ∆ Qa ÷ ∆ Pb
Qa Pb

Table
Demand for A Price of B
100 10
140 12

PbЄda = ∆ Qa ÷ ∆ Pb
Qa Pb
= 40 ÷ 2
100 10
= 2
Goods are substitutes (sign is positive). Demand is cross price elastic | є | > 1.

DETERMINANTS OF CROSS PRICE ELASTICITY OF DEMAND
• Time period
The longer the time period, the more will be the elasticity,
• Tastes and preferences
Taste and preferences can change.

INCIDENCE OF TAXATION
A tax results in a vertical shift of the supply curve as it increases the cost of producing the taxed
product.


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